sprague



No Model.) 2 Sheets-Sheet 1.

F. J. SPRAGU'E.

ELECTRIC RAILWAY. No. 340,684. Patented Apr. 27, 1886.

N4 PETERS. Pmwuma m her. Washinginn, D. c.

2 Sheets-Sheet 2.

(No Model.)

F. J. SPRAGUE.

ELECTRIC RAILWAY.

N0. 340,684. Patented Apr. 27, 1886.

UNITED STATES PATENT OEEIcE.

FRANK J. SPRAGUE, OF NEW YORK, N. Y.

ELECTRIC RAILWAY.

EP'EC'IPIC-ATION forming part of Letters Patent No. 340,684, dated April 27, 1886.

Serial No, 133,893, (No model.)

To aZZ whom it may concern.-

Be it known that I, FRANK J. SPRAGUE, of New York city, in the county and State of New York, have invented a certain new and useful Improvement in Electric Railways, of which the following is a specification.

In my Patent No. 318,668, dated May 26, 1885, is set forth a method of braking an electric-railway train by increasing the counter eleetro-motive force of the dynamo-eleetric machine, which normally acts as a motor propolling the train until the same exceeds the initial electromotive force on the line, whereby the machine becomes a generator, and the energy of the train is converted into current on the line. In employing this method, as is set forth :in said patent, when the machine is running as a generator, the diminution of speed of the armature tends to diminish its eleetro-motive force, which is counter to the electro-motive force on the line, and it is therefore necessary to keep on increasing the field-magnet strength, so as to still maintain this electro-motive force above that of the line. \Vhen, however, the limit of regulation of the iield is attained, this electro-motive force will begin to fall, and will equal or fall below the initial. It is then necessary to bring into operation other means for continuing to brake the train in order to bring it to a full stop. I accomplish this by providing the machine with a local circuit, in series with its armature, which is closed and the main armature-circuit broken, while the fieldcircuit (the machine being shunt-wound) is still left in connection with the line. There is thus formed a braking-generator with its field supplied from the line-current and its armature supplying a local circuit. The energy of the moving train is expended in this local circuit, and the train is stopped. The local circuit may include a suitable resistance, or it may include the operating magnet or magnets of an electromagnetic brake, which will be thrown into operation when the eircuit is closed. This latter feature forms no part of my present invention, but is included in another application for Letters Patent of even date herewith. The current expended in the local circuit may be regulated by ad justing the resistance in said circuit, or, preferably, by regulating the field-magnet oi" the machine. The resistance in the local circuit is preferably the usual armature-circuit re sistance, the circuit being arranged to include this. The field-magnet being supplied from an independent source, (the line,) its strength is independent of the armature-current and of the rate of motion of the train, and the current in the local circuit can therefore be made to depend upon the strength of the field, which, as stated, is regulated, preferably, by an adjustable resistance.

My invention is illustrated in the annexed drawings, in which Figure 1 is a plan View of a truck of an eleetrierailway car with the machine running as a motor, the circuits and regulating apparatus being shown in diagram; and Fig. 2 a similar View showing the same machine running as a braking-generator.

A is the truck of a car. 13 is the armature, and G the field-magnet, of a dynamo-electric machine, which normally runs as a propellinginotor, but is convertible into a brakinggenerator, as described. 3y eog-wheels I) D mo tion is communicated from the armatureshaft of the machine to the driving-axle E of the car when the machine is a motor, or from the axle to the shalt when it is a generator.

E F are the main rails of the track, forming one side of the circuit, and G is an intermedi ate rail forming the other side.

H is a generator supplying current to the railway. Contact-rollers I I run on the intermediate rail,while the connection to the main rails is by brush or spring a, resting on axle E and supported in any suitable manner.

The various switching and regulating de vices are shown, for convenience, as separate from the car. It will of course be understood that they are suitably placed upon or within the same.

K is the regulating apparatus for the armature and field circuits, which is such as is set forth in my Patent No. 321,150, dated June 30,1885. In this apparatus 1) I) are resistancecoils for the liehicircuit,connected with short contact-blocks c c and long block (I, and c e are coils for the armature-circuit connected, with short blocksf/"and long block g. .Pivoted arms h h travel on the contact-blocks.

L is the switch for throwing the armature from the line to the local circuit. it consists of two sets of three blocks each, i i. '1? and 7.: k

mature.

traveling on said blocks.

k, and two insulated contact-arms, Z and Z, I

Mis a reversing-switch for the armature circuit.

The circuits in Fig. 1 are as follows: from brush or spring a by wire 1 to arms h and h of switch K, where the circuits divide, the field-circuits being by resistance'coils b b to long block (I, wire2 to field-magnet,and wires 3 3 to contact-rollers I I, and the armaturecircuit is by h to long block g,wire 4 to block 0 of switch L, arm I to 1', wire 5 through reversingswitch M and wire 6 to motor-commutator, back to switch M by wire 7, and by wire 8 to block it of switch L, arm Z to k, and wire 9 to wires 3 3 and the contact-rollers.

As shown here,the machine is running as a motor in its ordinary manner,with no resistance in its armature-circuit, and it is regulated by varying the number of resistancecoils b in field-magnet circuit.

In Fig. 2 the construction and arrangement of apparatus are the same,- but here the machine is shown as converted into a generator and running on its local circuit. This is accomplished in the following manner: It being desired to stop the car or train, arms h h of switch Kare turned so as to remove resistancecoils b b from circuit, thereby strengthening the field and increasing the counter electromotive force in the armature-circuit. This is continued until the counter electro motive force overcomes the initial and the energy of the trains momentum is thrown in current upon the line but, as stated, the slowing down of the train causes a tendency to decrease the counter electro 1 motive force, so when the field is strengthened as much as it can be the counter electro-motive force will continue to decrease, the machine will again become a motor running at slow speed, and the train would not be stopped. When, however, the electro-motive forces become equal, which is shown by an indicator, S, of quantity and direction of current, switch L comes into play, and the change of its position to that of Fig. 2 changes the connection of the armature from the line to a local circuit, as follows: from one commutatorbrush by wire 6 to switch M, wire 5to block 1' of switch L, arm I to 1', wire 10 to switch K, through coils e e to arm h, wire 11 to block k of L, l to k, wire 8 to switch M, and wire 7 to other commutator-brush. The local circuit thus includes the resistance 6 e, and the energy expended therein is regulated by adjusting such resistance; or it may instead be regulated by adjusting the field-circuit resistance b b without affecting the armature-circuit resistance, the field remaining connected with the line, and supplied with current therefrom independent of the condition of the ar- Thevcoils of the resistance in the armaturecircuit are made of such size that they can carry all the current which passes in starting the motor, and therefore they cannot be injuriously affected by the braking-current.

The indicator S shows when the initial and counter electro-motive forces are equal, and also may be employed to show the amount of the armature-current when the machine is running as a motor, and of the braking-cub rent when it is'a generator.

It is evident that separate switches may be used to brake the main'armature-circuit and close the local circuit; but the single-movement switch is of course preferable.

Vh ile I have described my invention wholly with reference to a simple shunt-wound machine, it is evident that it is equally applicable to a compound machine having its main field-coils in shunt relation to the armature and other field-coils in series with the armatures. I

lVhat I claim is- 1. The combination, with a car or train of cars on an electric railway, of a braking-generator operated by the movement of said car or train, having its main field-magnet coils o supplied from the line and its armature supplying a local circuit, and an adjustable resistance in said local circuit, substantially as set forth. I

2. The combination, with a car or train of 5 cars on an electric railway, of a braking-generator operated by the movement of said car or train, having its main field-magnet coils supplied from the line and its armature supplying a local circuit, and means for regulat- 10o ing the strength of said field-magnet, substantially as set forth.

3. The combination, with a car or train of cars on an electric railway, of abraking-generator operated by the movement of said car or train,'having its main field-magnet coils supplied from the line and its armature supplying a local circuit, and an adjustable resistance for regulating the current supplied to said main field-magnet coils, substantially as no set forth.

4. The combination, with a car or train of cars on an electric railway, of a'braking-generator operated by the movement of said car or train, having its main field-magnet coils supplied from the lines,and its armature supplying a local circuit, a resistance in saidlocal circuit, and means for regulating the strength of said field-magnet, substantiallyas set forth.

7 5. The combination, with a car or train of I20 cars on an electric railway, of a bl'akinggenerator operated by the movement of said car 1 or train, having its main field-magnet coils supplied from the line and its armature supplying a local circuit, an adjustable resistance in said local circuit, and an adjustable resistance for regulating the current supplied to said main field-magnet coils, substantially as set forth.

6. The combination, with a car or train of 1 0 cars on an electric railway, of a dynamo-electric machine having its armatureshaft connected mechanically with a driving-axle, and its main field-magnet coils permanently connected electrically with the line, means for regulating the strength of said field-magnet, a local armature-circuit, and means for connecting the armature electrically either with said local circuit or with the line, substantially as set forth 7. The combination, with an electric rail- IO way, of a dynamoelectric machine adapted to be used either as a propelling-motor or abrakjug-generator and a device indicating strength and direction of current in the armature-circuit thereof, substantially as set forth.

This specification signed and witnessed this I 5 7th day of November, 1885.

FRANK J. PRAGUE. Witnesses:

A. XV. KIDDLE, E. O ROXVLAND. 

